1. Field of the Invention
The present invention relates to a method for measuring characteristics of electronic parts including at the measuring of insulating resistance of the electronic parts. More particularly, the present invention relates to a method of measuring insulation resistance values of electronic parts with a process of serially and intermittently carrying a plurality of electronic parts along a circulation path.
2. Description of the Background Art
In advance to the shipment of capacitors, for example, an inspection step is generally carried out for measuring electronic characteristics such as capacitance and insulation resistance, and the capacitors are selected on the basis of the results of such measurement.
A manufacturer shipping a large quantity of capacitors must efficiently carry out the aforementioned inspection step. FIG. 2 shows a characteristic measuring apparatus which is generally employed for measuring the characteristics of chip capacitors, for example.
Referring to FIG. 2, the characteristic measuring apparatus comprises a turntable 1, which is intermittently fed in the direction of an arrow 2. In the periphery of the turntable 1, a plurality of holding portions 3 are distributed at regular intervals for holding the chip capacitors individually
A parts feeder 4 is adapted to supply a plurality of chip capacitors. When the turntable 1 is intermittently fed in the direction of arrow 2, therefore, the chip capacitors are successively supplied to the respective holding portions 3 one by one from a supply position 5.
The characteristics of the chip capacitors thus held by the holding portions 3 are measured in the following manner during intermittent feeding of the turntable 1.
First, capacitance values are measured at a capacitance measuring position 6.
Then, the chip capacitors are charged in a charge region 7. Thereafter insulation resistance values of the charged chip capacitors are measured in a measuring position 8. Then the charges stored in the chip capacitors are discharged in a discharge portion 9.
The chip capacitors held by the holding portions 3 are then selected on the basis of the results of the aforementioned characteristic measurement and removed at an outlet position 13.
In the aforementioned method of measuring the characteristics, however, the chip capacitors are merely intermittently charged in the charge region 7. This is because charging terminals come into contact with the chip capacitors only when the turntable 1 is stopped, and no contact is attained between the charging terminals and the chip capacitors during rotation of the turntable 1. Thus, charging efficiency is so deteriorated that the chip capacitors may not be completely charged. As a result, it may not be possible to measure the insulation resistance values with high accuracy.. In order to measure the insulation resistance values with high accuracy, the interval for intermittently feeding the turntable 1 must be increased. Thus, it is impossible to measure characteristics of a number of chip capacitors at a high speed. Such a tendency remarkably appears in the case of chip capacitors having particularly high capacitance values.
In order to obtain a long charging time, the area of the charge region 7 may be increased. In this case, however, it is not the size of the turntable 1 in view of area efficiency in the factory.
Further, since the charging time depends upon the provision of the charge region 7, it is impossible to undertake characteristic measurements of various types of chip capacitors. The above method also applies to the measurement of insulation resistance of inductors, LC filters like in addition to capacitors, while the characteristics to be measured may also include impedance, inductance and the like.